During the process of transmitting binary data or transforming binary data from one medium to another, bits may be lost. Bit loss, for example, would be likely to occur due to some permanent, transient or intermittent faults. Various means for detecting errors have been used. Hamming codes have the advantage of being able to detect two errors in a data field, and also to correct a one-bit error. When Hamming codes are used in conjunction with other codes (parity checks, check sums, etc.) the detection of any number of error bits, or the corrosion of one error bit per record is obtainable. However, a fault that occurs inside a Hamming encoder/decoder circuit may lead to erroneous detection results of the Hamming decoder. In other words, the fault occurs in the Hamming encoder/decoder circuit itself is generally undetectable by the Hamming decoder.